Operating Systems 2019W: Assignment 4 - Revision history

Soma at 20:34, 10 April 2019

2019-04-10T20:34:53Z

Soma: /* Multiple choice questions */

2019-04-09T02:44:27Z

Multiple choice questions

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	</ol>		</ol>
	</li>		</li>
	<li> An implementation of a semaphore ~~test~~ the value of the semaphore and changes it if the semaphore is available. What makes it hard to write a good semaphore implementation?		<li> An implementation of a semaphore tests the value of the semaphore and changes it if the semaphore is available. What makes it hard to write a good semaphore implementation?
	<ol type="A">		<ol type="A">
	<li> semaphore operations should be fast</li>		<li> semaphore operations should be fast</li>

Soma: /* Multiple choice questions */

2019-04-09T01:49:25Z

Multiple choice questions

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	<ol type="A">		<ol type="A">
	<li> The kernel sends SIGSTOP to the terminal and causes bc to pause.</li>		<li> The kernel sends SIGSTOP to the terminal and causes bc to pause.</li>
	<li> Highlighted text gets copied to the clipboard.</li>		<li> Highlighted text gets copied to the clipboard on Linux.</li>
	<li> bc sends SIGTERM to itself and exits.</li>		<li> bc sends SIGTERM to itself and exits.</li>
	<li> bc sends SIGINT to itself and exits.</li>		<li> bc sends SIGINT to itself and exits.</li>

Soma: /* Multiple choice questions */

2019-04-08T01:30:18Z

Multiple choice questions

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	<li> Debian</li>		<li> Debian</li>
	<li> Gentoo</li>		<li> Gentoo</li>
			</ol>
	</li>		</li>
	<li>Which of the following operations are permitted for an unprivileged user?		<li>Which of the following operations are permitted for an unprivileged user?

Soma at 01:29, 8 April 2019

2019-04-08T01:29:26Z

Show changes

Soma: /* Questions */

2019-04-02T20:38:08Z

Questions

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	# [2] Does the ssh command use random numbers? How can you demonstrate this?		# [2] Does the ssh command use random numbers? How can you demonstrate this?
	# [2] Can a setuid root process give up its privileges and run as a regular user? Is this change necessarily permanant?		# [2] Can a setuid root process give up its privileges and run as a regular user? Is this change necessarily permanant?
	# [2] What are the main factors that influence whether the attacker wins the race with ~~3000run~~-write? Explain what it means for the attacker to win.		# [2] What are the main factors that influence whether the attacker wins the race with 3000log-write? Explain what it means for the attacker to win.

Soma: /* Questions */

2019-04-01T23:55:22Z

Questions

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	# [2] When you hit Ctrl-C while running the bc command, does the Ctrl-C generate a signal? How do you know?		# [2] When you hit Ctrl-C while running the bc command, does the Ctrl-C generate a signal? How do you know?
	# [2] Does bashreadline report commands given to bash via shell scripts? How do you know?		# [2] Does bashreadline report commands given to bash via shell scripts? How do you know?
	# [2] How can you modify 3000pc so the producer stops on the third time it fills its queue? Give your code as a diff -c versus the original 3000pc		# [2] How can you modify 3000pc so the producer stops on the third time it fills its queue? Give your code as a diff -c versus the original 3000pc.
	# [2] Under what conditions would 3000pc never send a signal (from the producer to the consumer or vice versa)? How could you modify 3000pc so this occurance was more likely?		# [2] Under what conditions would 3000pc never send a signal (from the producer to the consumer or vice versa)? How could you modify 3000pc so this occurance was more likely?
	# [2] Implement and critique your own version of sem_wait() and sem_post() in pure C with no system calls. Do you think your version is free of race conditions? Explain.		# [2] Implement and critique your own version of sem_wait() and sem_post() in pure C with no system calls. Do you think your version is free of race conditions? Explain.

Soma: /* Questions */

2019-04-01T23:39:15Z

Questions

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	# [2] Under what conditions would 3000pc never send a signal (from the producer to the consumer or vice versa)? How could you modify 3000pc so this occurance was more likely?		# [2] Under what conditions would 3000pc never send a signal (from the producer to the consumer or vice versa)? How could you modify 3000pc so this occurance was more likely?
	# [2] Implement and critique your own version of sem_wait() and sem_post() in pure C with no system calls. Do you think your version is free of race conditions? Explain.		# [2] Implement and critique your own version of sem_wait() and sem_post() in pure C with no system calls. Do you think your version is free of race conditions? Explain.
	# [2] Change ~~300pc~~ so that uses a shared memory mapped file rather than simply shared memory to communicate between the producer and consumer. How big is the file? Does its size change?		# [2] Change 3000pc so that uses a shared memory mapped file rather than simply shared memory to communicate between the producer and consumer. How big is the file? Does its size change?
	# [2] How difficult is it for a userspace process to generate truly random numbers on its own, without the assistance of the kernel? Explain.		# [2] How difficult is it for a userspace process to generate truly random numbers on its own, without the assistance of the kernel? Explain.
	# [2] Does the ssh command use random numbers? How can you demonstrate this?		# [2] Does the ssh command use random numbers? How can you demonstrate this?
	# [2] Can a setuid root process give up its privileges and run as a regular user? Is this change necessarily permanant?		# [2] Can a setuid root process give up its privileges and run as a regular user? Is this change necessarily permanant?
	# [2] What are the main factors that influence whether the attacker wins the race with 3000run-write? Explain what it means for the attacker to win.		# [2] What are the main factors that influence whether the attacker wins the race with 3000run-write? Explain what it means for the attacker to win.

Soma at 23:37, 1 April 2019

2019-04-01T23:37:25Z

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	For this assignment please work on the questions below. While you will be able to submit your answers, by ~~defalt~~ '''they will not be graded.''' Instead, an approximately 20 question multiple choice quiz (based on the questions below) will be made available by April 8 and will be due by 4 PM on April 10th. The grade for this quiz will substitute for Assignment 4.		For this assignment please work on the questions below. While you will be able to submit your answers, by default '''they will not be graded.''' Instead, an approximately 20 question multiple choice quiz (based on the questions below) will be made available by April 8 and will be due by 4 PM on April 10th. The grade for this quiz will substitute for Assignment 4.

	In class on April 10th solutions for the assignment questions below and the Assignment 4 Quiz will be given and discussed.		In class on April 10th solutions for the assignment questions below and the Assignment 4 Quiz will be given and discussed.

Soma at 23:15, 1 April 2019

2019-04-01T23:15:37Z

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	In class on April 10th solutions for the assignment questions below and the Assignment 4 Quiz will be given and discussed.		In class on April 10th solutions for the assignment questions below and the Assignment 4 Quiz will be given and discussed.

	If you feel your answers to the quiz do not demonstrate what you actually learned, you can make an appointment with Prof. Somayaji to grade your submitted Assignment 4 answers (assuming you submitted them by April 10th).		If you feel your answers to the quiz do not demonstrate what you actually learned, you can make an appointment with Prof. Somayaji to grade your submitted Assignment 4 answers (assuming you submitted them by April 10th) before April 19th.

	==Questions==		==Questions==